The broad goal of this research program is to explore how the human infant comes to represent objects and events in the world. The experiments take the form of studying how infants learn to coordinate their actions with the demands of the environmental input. Studies are proposed of reaching, grasping, and looking in settings that impose limits on how success can be achieved. Such manipulations should uncover how perception and action become increasingly coordinated throughout the first two years of life. Reaching and grasping are regarded as overt reflections of planning and adjustment to object properties. Inferences will be drawn about the cognition underlying these behaviors. A motion analysis system consisting of Optotrak sensor bars will allow precise measurement of hand position in 3-dimensional space and hand movement in relation to object movement. The use of infrared video recording allows measurement of the effect of sight of the object and sight of the hand on control of reaching. Both looking and reaching will be recorded in experimental settings. Motor errors, error corrections, latency to produce motor actions of varying complexity, and kinematics of the reach itself are assumed to reveal the processes underlying representation. The coordination of looking with reaching behavior will be studied through analysis of the videorecord and the kinematic measures provided by the motion analysis system. Some studies will present infants between 6 and 24 months of age with moving objects (for example, a rolling ball) that disappears and reappears from behind a screen. The anticipated trajectory of the hidden ball should be reflected in the infant's anticipatory actions, shown by the latency and kinematics of the reach. Another set of studies involves infants and toddlers' learning to grasp objects in a way appropriate to achieve some goal. By using a variety of tasks and measures the project should provide information concerning the normal development of perception, motor control, and cognition in the human infant.